Synthesis gas, or “syngas,” is the name given to a gas mixture that contains varying amounts of carbon oxides (such as carbon monoxide) and hydrogen. The name comes from their use as intermediates in creating synthetic natural gas, ammonia, methyl alcohol (methanol), or fuels.
Syngas can be generated in many ways, for example, by the gasification of a carbon containing fuel to a gaseous product with a heating value, e.g., gasification of coal, biomass or municipal waste materials. Other examples include the steam reforming of natural gas, methane from various sources, or liquid hydrocarbons. Syngas is combustible and often used as a fuel source or as an intermediate for the production of other chemicals. Syngas is also used as an intermediate in producing synthetic petroleum for use as a fuel or lubricant via catalysis using a Fisher-Tropsch catalyst. Syngas for use as a fuel is most often produced by gasification of coal or municipal waste.
When used as an intermediate in the large-scale, industrial synthesis of hydrogen and ammonia, it is also produced from natural gas (via the steam reforming reaction). The syngas produced in large waste-to-energy gasification facilities is used as fuel to generate electricity. Coal gasification processes are reasonably efficient and were used for many years to manufacture what used to be known as “illuminating” gas, or coal gas, for lighting in street lamps and homes before electricity became widely available.
Synthesis gas is widely used to produce methanol. Synthesis gas from coal is also used to produce an array of chemicals. It can be catalysed to produce a class of diesel fuel called “Fisher-Tropsch fuels”.
Recently, specialized bacteria have been developed to convert synthesis gas into a mixture of ethanol and acetic acid. The chemical pathway to ethanol is not efficient in these one-step processes.
There have also been disclosed a number of methods for synthesizing ethanol directly from biomass using fermentation or other biological processes. While these processes have been used to produce ethanol from the cellulose contained in biomass, such processes are severely limited by, among other things, their inability to convert the lignins contained in lignocellulosic biomass to useful products.
Disclosed is a process by which synthesis gas is efficiently converted into ethanol, requiring little purification and water removal. This ethanol is suitable as an alternative fuel, for industrial use, as a chemical precursor, or as an additive in pharmaceuticals or beverages.
Ethyl alcohol (ethanol) is a global product which is used for beverages, industrial processes and more recently as a fuel for combustion engines which is cleaner burning than gasoline.
Because the world demand for ethanol is so great and will now grow incredibly with the attempt to use it as a fuel additive on a large scale here in North America, a process that utilizes whole biomass would increase global ethanol capacity.
The subject invention describes a method by which the synthesis gas which is produced from biomass material can be efficiently converted into ethanol.